I'll try to find an alternative link for it. Also, there is an extended edition (with an additional half an hour) of this programme due to be broadcast on Saturday 14th May 21.00 - 22.30 GMT. I'll update the previous link when it becomes available.

Link updated to reflect the more recent 90 minute version of the documentary. Also I changed what is linked to - now it's the introductory page from which a link to the actual iPlayer programme is made.